gimp: add gimp-with-plugin derivation

By default all plugins from pkgs.gimpPlugins set are enabled.

Default location of plugins changed from $out/${gimp.name} to
$out/lib/gimp/${majorVersion}. Resulting derivation for gimp+plugins
is set as search path for plugins by default (additional tweaking in
gimprc done for old plugin scheme should be removed)

pkgs/applications/graphics/gimp/wrapper.nix

@@ -0,0 +1,33 @@
+{ stdenv, lib, buildEnv, gimp, makeWrapper, gimpPlugins, plugins ? null}:
+
+let
+allPlugins = lib.filter (pkg: builtins.isAttrs pkg && pkg.type == "derivation") (lib.attrValues gimpPlugins);
+selectedPlugins = if plugins == null then allPlugins else plugins;
+extraArgs = map (x: x.wrapArgs or "") selectedPlugins;
+
+drv = buildEnv {
+  name = "gimp-with-plugins-" + (builtins.parseDrvName gimp.name).version;
+
+  paths = [ gimp ] ++ selectedPlugins;
+
+  postBuild = ''
+    # TODO: This could be avoided if buildEnv could be forced to create all directories
+    if [ -L $out/bin ]; then
+      rm $out/bin
+      mkdir $out/bin
+      for i in ${gimp}/bin/*; do
+        ln -s $i $out/bin
+      done
+    fi
+    for each in gimp-2.8 gimp-console-2.8; do
+      wrapProgram $out/bin/$each \
+        --set GIMP2_PLUGINDIR "$out/lib/gimp/2.0" \
+        ${toString extraArgs}
+    done
+    set +x
+    for each in gimp gimp-console; do
+      ln -sf "$each-2.8" $out/bin/$each
+    done
+  '';
+  };
+in stdenv.lib.overrideDerivation drv (x : { buildInputs = x.buildInputs ++ [ makeWrapper ]; })